Power transmitting apparatus for vehicle

ABSTRACT

A power transmitting apparatus for a vehicle achieves seven forward speeds with a minimal number of input gears disposed on input shafts, since the second speed gear and the fourth speed gear are simultaneously engaged with the second input gear and the third speed gear and the seventh speed gear are simultaneously engaged with the third input gear, and distortion of step ratios at the high-speed region may be prevented.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent ApplicationNumber 10-2012-0136464 filed Nov. 28, 2012, the entire contents of whichapplication is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a double clutch power transmittingapparatus. More particularly, the present invention relates to a powertransmitting apparatus for a vehicle which improves mountability byminimizing a length of the power transmitting apparatus and enhancesdrivability and fuel economy by preventing distortion of step ratios.

2. Description of Related Art

Environmentally-friendly technique of vehicles is very importanttechnique on which survival of future motor industry is dependent.Vehicle makers are focusing on development of environmentally-friendlyvehicles so as to meet environment and fuel consumption regulations.

Some examples of future vehicle technique are an electric vehicle (EV)and a hybrid electric vehicle (HEV) that use electrical energy, anddouble clutch transmission (DCT) that improves efficiency andconvenience.

The DCT includes two clutch devices and a gear train applied to a manualtransmission. The DCT selectively transmits torque input from an engineto two input shafts by using two clutches, changes a speed by using thegear train, and outputs the changed torque.

Such the DCT is used to realize a compact transmission having more thanfive forward speeds. Since two clutches and synchronizing devices arecontrolled by a controller according to the DCT, manual shift maneuveris unnecessary for controlling the DCT. Therefore, the DCT is one typeof automated manual transmissions (AMT).

The DCT, compared with an automatic transmission using planetary gearsets, has excellent power delivery efficiency and change and addition ofcomponents is very easy in the DCT. Therefore, the DCT can meet fuelconsumption regulations and multi-speeds efficiency may be improved.

The information disclosed in this Background section is only forenhancement of understanding of the general background of the inventionand should not be taken as an acknowledgement or any form of suggestionthat this information forms the prior art already known to a personskilled in the art.

BRIEF SUMMARY

Various aspects of the present invention provide for a powertransmitting apparatus for a vehicle having advantages of improvingmountability by minimizing a length of the power transmitting apparatusand enhancing drivability and fuel economy by preventing distortion ofstep ratios.

A power transmitting apparatus for a vehicle according to one aspect ofthe present invention may include: a variable connecting deviceincluding a first clutch and a second clutch and selectively outputtingtorque of an engine through the first clutch and the second clutch; aninput device including a first input shaft selectively connected to theengine through the second clutch and provide with first, second, andsixth input gears fixedly disposed on an exterior circumference thereof,and a second input shaft selectively connected to the engine through thefirst clutch and provided with third, fourth, and fifth input gearsfixedly disposed on an exterior circumference thereof; a speed outputdevice including a first output shaft disposed in parallel with thefirst and second input shafts, a first speed output unit disposed on thefirst output shaft and provided with first and second synchronizermodules, a second output shaft disposed in parallel with the first andsecond input shafts, and a second speed output unit disposed on thesecond output shaft and provided with third and fourth synchronizermodules; a reverse speed device including a reverse speed shaft and anidle gear and a reverse input gear fixedly disposed on the reverse speedshaft, wherein the idle gear is engaged with any one input gear on thefirst and second input shafts and the reverse input gear is engaged withany one synchronizer module disposed on the first output shaft; andfirst, second, third, fourth, fifth, sixth, and seventh speed gears anda reverse speed gear included in the first, second, third, and fourthsynchronizer modules, wherein the second speed gear and the fourth speedgear are simultaneously engaged with the second input gear disposed onthe first input shaft, and the third speed gear and the seventh speedgear are simultaneously engaged with the third input gear disposed onthe second input shaft.

The first input shaft may be a hollow shaft and the sixth, first andsecond input gears may be disposed on the exterior circumference of thefirst input shaft in a named sequence from a front portion to a rearportion. At least a portion of the second input shaft may be inserted inthe first input shaft, and the third, fifth and fourth input gears maybe disposed on a portion of the second input shaft penetrating the firstinput shaft in a named sequence from a front portion to a rear portion.

The first synchronizer module may include the third speed gear engagedwith the third input gear and the first speed gear engaged with thefifth input gear.

The second synchronizer module may include the reverse speed gearengaged with the reverse input gear connected to the idle gear engagedwith the sixth input gear through the reverse speed shaft, and thesecond speed gear engaged with the second input gear.

The third synchronizer module may include the sixth speed gear engagedwith the first input gear and the fourth speed gear engaged with thesecond input gear.

The fourth synchronizer module may include the seventh speed gearengaged with the third input gear and the fifth speed gear engaged withthe fourth input gear.

The sixth, first and second input gears may be disposed on the exteriorcircumference of the first input shaft in a named sequence from a frontportion to a rear portion. The second input shaft may be a hollow shaftand the third, fifth and fourth input gears may be disposed on theexterior circumference of the second input shaft in a named sequencefrom a front portion to a rear portion. At least a portion of the firstinput shaft may be inserted in the second input shaft.

The first synchronizer module may include the third speed gear engagedwith the third input gear and the first speed gear engaged with thefifth input gear.

The second synchronizer module may include the reverse speed gearengaged with the reverse input gear connected to the idle gear engagedwith the sixth input gear through the reverse speed shaft, and thesecond speed gear engaged with the second input gear.

The third synchronizer module may include the sixth speed gear engagedwith the first input gear and the fourth speed gear engaged with thesecond input gear.

The fourth synchronizer module may include the seventh speed gearengaged with the third input gear and the fifth speed gear engaged withthe fourth input gear.

A power transmitting apparatus for a vehicle according to another aspectof the present invention may include: a first clutch connected to anengine and selectively outputting torque of the engine; a second clutchconnected to the engine and selectively outputting the torque of theengine; a first input shaft being a hollow shaft, selectively receivingthe torque of the engine through the second clutch, and provided withsixth, first and second input gears disposed on an exteriorcircumference thereof in a named sequence; a second input shaftpenetrating the first input shaft without rotational interferencetherebetween, selectively receiving the torque of the engine through thefirst clutch, and provided with third, fifth and fourth input gearsdisposed on an exterior circumference thereof in a named sequence; firstand second output shafts disposed in parallel with the first and secondinput shafts; a first synchronizer module disposed on the first outputshaft, and including a third speed gear engaged with the third inputgear and a first speed gear engaged with the fifth input gear; a secondsynchronizer module disposed on the first output shaft, and including areverse speed gear engaged with a reverse input gear connected to anidle gear engaged with the sixth input gear through a reverse speedshaft and a second speed gear engaged with the second input gear; athird synchronizer module disposed on the second output shaft, andincluding a sixth speed gear engaged with the first input gear and afourth speed gear engaged with the second input gear; and a fourthsynchronizer module disposed on the second output shaft, and including aseventh speed gear engaged with the third input gear and a fifth speedgear engaged with the fourth input gear.

A power transmitting apparatus for a vehicle according to other aspectof the present invention may include: a first clutch connected to anengine and selectively outputting torque of the engine; a second clutchconnected to the engine and selectively outputting the torque of theengine; a first input shaft selectively receiving the torque of theengine through the second clutch and provided with sixth, first andsecond input gears disposed on an exterior circumference thereof in anamed sequence; a second input shaft being a hollow shaft, selectivelyreceiving the torque of the engine through the first clutch, andprovided with third, fifth and fourth input gears disposed on anexterior circumference thereof in a named sequence, at least a portionof the first input shaft being inserted in the second input shaft; firstand second output shafts disposed in parallel with the first and secondinput shafts; a first synchronizer module disposed on the first outputshaft, and including a third speed gear engaged with the third inputgear and a first speed gear engaged with the fifth input gear; a secondsynchronizer module disposed on the first output shaft, and including areverse speed gear engaged with a reverse input gear connected to anidle gear engaged with the sixth input gear through a reverse speedshaft and a second speed gear engaged with the second input gear; athird synchronizer module disposed on the second output shaft, andincluding a sixth speed gear engaged with the first input gear and afourth speed gear engaged with the second input gear; and a fourthsynchronizer module disposed on the second output shaft, and including aseventh speed gear engaged with the third input gear and a fifth speedgear engaged with the fourth input gear.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary power transmittingapparatus for a vehicle according to the present invention.

FIG. 2 is an operational chart of an exemplary power transmittingapparatus for a vehicle according to the present invention.

FIG. 3 is a schematic diagram of an exemplary power transmittingapparatus for a vehicle according to the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Description of components that are not necessary for explaining thevarious embodiments will be omitted, and the same constituent elementsare denoted by the same reference numerals in this specification.

In the detailed description, ordinal numbers are used for distinguishingconstituent elements having the same terms, and have no specificmeanings.

FIG. 1 is a schematic diagram of a power transmitting apparatus for avehicle according to the present invention.

Referring to FIG. 1, a power transmitting apparatus according to variousembodiments of the present invention includes a variable connectingdevice CL1 and CL2, an input device IS1 and IS2, a speed output deviceOUT1 and OUT2, and a reverse speed device RS, ID, and RIG.

The variable connecting device includes first and second clutches CL1and CL2.

The first clutch CL1 and the second clutch CL2 selectively transmitstorque of an engine ENG that is a power source respectively to a secondinput shaft IS2 and a first input shaft IS1.

The first clutch CL1 selectively connects the second input shaft IS2with an output side of the engine ENG, and the second clutch CL2selectively connects the first input shaft IS1 with the output side ofthe engine ENG.

The first and second clutches CL1 and CL2 forming the variableconnecting device may be conventional multi-plate clutches of wet type,and are controlled by a hydraulic control system.

The input device includes the first and second input shafts IS1 and IS2.

The first input shaft IS1 is a hollow shaft, and a front end portion ofthe first input shaft IS1 is selectively connected to the output side ofthe engine ENG through the second clutch CL2.

In addition, sixth, first and second input gears G6, G1, and G2 aredisposed on the first input shaft IS1 with predetermined distances in anamed sequence from a front portion to a rear portion.

The second input shaft IS2 is inserted in the first input shaft IS1without rotational interference with the first input shaft IS1. A frontend portion of the second input shaft IS2 is selectively connected tothe output side of the engine ENG through the first clutch CL1.

In addition, third, fourth, and fifth input gears G3, G4, and G5 aredisposed on the second input shaft IS2 with predetermined distances. Thethird, fourth, and fifth input gears G3, G4, and G5 are positioned at arear portion of the second input shaft IS2 penetrating the first inputshaft IS1 and are disposed in a sequence of the third, fifth, and fourthinput gears G3, G5, and G4 from a front portion to a rear portion.

The first, second, third, fourth, fifth, and sixth input gears G1, G2,G3, G4, G5, and G6 are input gears operating at each speed. That is, thefirst input gear G1 is operated at a sixth forward speed, the secondinput gear G2 is operated at a second forward speed and a fourth forwardspeed, the third input gear G3 is operated at a third forward speed anda seventh forward speed, the fourth input gear G4 is operated at a fifthforward speed, the fifth input gear G5 is operated at a first forwardspeed, and the sixth input gear G6 is operated at a reverse speed.

That is, the input gears for even-numbered speeds and the reverse speedare disposed on the first input shaft IS1, and the input gears forodd-numbered speeds are disposed on the second input shaft IS2.

The speed output device is adapted to receive torque from each inputgear of the input device, convert torque, and output the convertedtorque. The speed output device includes first and second speed outputunits OUT1 and OUT2 disposed in parallel with the first and second inputshafts IS1 and IS2.

The first speed output unit OUT1 includes a first output shaft OS1disposed in parallel with the first and second input shafts IS1 and IS2,a first synchronizer module SL1 including a first speed gear D1 and athird speed gear D3, and a second synchronizer module SL2 including asecond speed gear D2 and a reverse speed gear RG.

The first synchronizer module SL1 is disposed on a rear portion of thefirst output shaft OS1, and the second synchronizer module SL2 isdisposed on a front portion of the first output shaft OS1.

The first speed gear D1 of the first synchronizer module SL1 is engagewith the fifth input gear G5, and the third speed gear D3 of the firstsynchronizer module SL1 is engaged with the third input gear G3.

The second speed gear D2 of the second synchronizer module SL2 isengaged with the second input gear G2.

In addition, the torque converted by the first speed output unit OUT1 istransmitted to a conventional differential device through a first outputgear OG1 mounted at a front end portion of the first output shaft OS1.

The second speed output unit OUT2 includes a second output shaft OS2disposed in parallel with the first and second input shafts IS1 and IS2,a third synchronizer module SL3 including a sixth speed gear D6 and afourth speed gear D4, and a fourth synchronizer module SL4 including aseventh speed gear D7 and a fifth speed gear D5.

The third synchronizer module SL3 is disposed on a front portion of thesecond output shaft OS2 and the fourth synchronizer module SL4 isdisposed on a rear portion of the second output shaft OS2.

The sixth speed gear D6 of the third synchronizer module SL3 is engagedwith the first input gear G1, and the fourth speed gear D4 of the thirdsynchronizer module SL3 is engaged with the second input gear G2.

The seventh speed gear D7 of the fourth synchronizer module SL4 isengaged with the third input gear G3, and the fifth speed gear D5 of thefourth synchronizer module SL4 is engaged with the fourth input gear G4.

In addition, the torque converted by the second speed output unit OUT2is transmitted to the conventional differential device through thesecond output gear OG2 mounted at a front end portion of the secondoutput shaft OS2.

The reverse speed device includes a reverse speed shaft RS, and an idlegear ID and a reverse input gear RIG integrally formed with the reversespeed shaft RS. One will appreciate that such integral components may bemonolithically formed.

The idle gear ID is engaged with the sixth input gear G6, and thereverse input gear RIG is engaged with the reverse speed gear RG.Therefore, if the first input shaft IS1 rotates, torque of the sixthinput gear G6 is transmitted to the reverse speed gear RG as an inverserotation speed and the inverse rotation speed is transmitted to theconventional differential device through the first output shaft OS1.

Since the first, second, third, and fourth synchronizer modules SL1,SL2, SL3, and SL4 are well known to a person of an ordinary skill in theart, detailed description thereof will be omitted. In addition, sleevesSLE1, SLE2, SLE3, and SLE4 applied respectively to the first, second,third, and fourth synchronizer modules SL1, SL2, SL3, and SL4, as wellknown to a person of an ordinary skill in the art, are operated byadditional actuators and the actuators are controlled by a transmissioncontrol unit.

FIG. 2 is an operational chart of various embodiments including thepower transmitting apparatus of FIG. 1.

Reverse Speed

At the reverse speed R, as shown in FIG. 2, the first output shaft OS1and the reverse speed gear RG are operably connected by the sleeve SEL2of the second synchronizer module SL2. After that, the second clutch CL2is operated. Then, shift to the reverse speed is completed.

First Forward Speed

At the first forward speed 1^(ST), as shown in FIG. 2, the first speedgear D1 and the first output shaft OS1 are operably connected by thesleeve SEL1 of the first synchronizer module SL1. After that, the firstclutch CL1 is operated. Then, shift to the first forward speed iscompleted.

Second Forward Speed

If vehicle speed increases at the first forward speed 1^(ST) and shiftto the second forward speed 2^(ND) is necessary, as shown in FIG. 2, thesecond speed gear D2 and the first output shaft OS1 are operablyconnected by the sleeve SEL2 of the second synchronizer module SL2.After that, the first clutch CL1 is released and the second clutch CL2is operated. Then, the shift to the second forward speed is completed.

After the shift to the second forward speed is completed, the sleeveSEL1 of the first synchronizer module SL1 is moved to a neutralposition.

Third Forward Speed

If the vehicle speed increases at the second forward speed 2^(ND) andshift to the third forward speed 3^(RD) is necessary, as shown in FIG.2, the third speed gear D3 and the first output shaft OS1 are operablyconnected by the sleeve SEL1 of the first synchronizer module SL1. Afterthat, the second clutch CL2 is released and the first clutch CL1 isoperated. Then, the shift to the third forward speed is completed.

After the shift to the third forward speed is completed, the sleeve SEL2of the second synchronizer module SL2 is moved to a neutral position.

Fourth Forward Speed

If the vehicle speed increases at the third forward speed 3^(RD) andshift to the fourth forward speed 4^(TH) is necessary, as shown in FIG.2, the fourth speed gear D4 and the second output shaft OS2 are operablyconnected by the sleeve SEL3 of the third synchronizer module SL3. Afterthat, the first clutch CL1 is released and the second clutch CL2 isoperated. Then, the shift to the fourth forward speed is completed.

After the shift to the fourth forward speed is completed, the sleeveSEL1 of the first synchronizer module SL1 is moved to the neutralposition.

Fifth Forward Speed

If the vehicle speed increases at the fourth forward speed 4^(TH) andshift to the fifth forward speed 5^(TH) is necessary, as shown in FIG.2, the fifth speed gear D5 and the second output shaft OS2 are operablyconnected by the sleeve SEL4 of the fourth synchronizer module SL4.After that, the second clutch CL2 is released and the first clutch CL1is operated. Then, the shift to the fifth forward speed is completed.

After the shift to the fifth forward speed is completed, the sleeve SEL3of the third synchronizer module SL3 is moved to a neutral position.

Sixth Forward Speed

If the vehicle speed increases at the fifth forward speed 5^(TH) andshift to the sixth forward speed 6^(TH) is necessary, as shown in FIG.2, the sixth speed gear D6 and the second output shaft OS2 are operablyconnected by the sleeve SEL3 of the third synchronizer module SL3. Afterthat, the first clutch CL1 is released and the second clutch CL2 isoperated. Then, the shift to the sixth forward speed is completed.

After the shift to the sixth forward speed is completed, the sleeve SEL4of the fourth synchronizer module SL4 is moved to a neutral position.

Seventh Forward Speed

If the vehicle speed increases at the sixth forward speed 6^(TH) andshift to the seventh forward speed 7^(TH) is necessary, as shown in FIG.2, the seventh speed gear D7 and the second output shaft OS2 areoperably connected by the sleeve SEL4 of the fourth synchronizer moduleSL4. After that, the second clutch CL2 is released and the first clutchCL1 is operated. Then, the shift to the seventh forward speed iscompleted.

After the shift to the seventh forward speed is completed, the sleeveSEL3 of the third synchronizer module SL3 is moved to the neutralposition.

In the power transmitting apparatus according to various embodimentsincluding that shown in FIG. 1, the second speed gear D2 and the fourthspeed gear D4 are simultaneously engaged to the second input gear G2 andthe third speed gear D3 and the seventh speed gear D7 are simultaneouslyengaged to the third input gear G3.

Since seven forward speeds can be achieved but the number of input gearsdisposed on the input shafts can be minimized, it is unnecessary toelongate a length of the input shafts. Therefore, layout change ofengine compartments and other design change due to increase of thelength of the transmission may be prevented.

In addition, step ratios between shift steps are large at a low-speedregion where higher output is necessary but are small at a high-speedregion where quick shift and driving efficiency is necessary. The secondspeed gear D2 and the fourth speed gear D4 having comparatively largegear ratio difference therebetween are simultaneously engaged to thesecond input gear G2, and the third speed gear D3 and the seventh speedgear D7 having comparatively large gear ratio difference therebetweenare simultaneously engaged to the third input gear G3 in the apparatusof FIG. 1. Therefore, drivability and fuel economy may be improved bypreventing distortion of step ratios at the high-speed region.

FIG. 3 is a schematic diagram of a power transmitting apparatus for avehicle according to various embodiments of the present invention.

Referring to FIG. 3, the second and third synchronizer modules SL2 andSL3 for the even-numbered speeds are disposed at the front end portionsof the output shafts OS1 and OS2 in the apparatus of FIG. 1, but thesecond and third synchronizer modules SL2 and SL3 for the even-numberedspeeds are disposed at the rear end portion of the output shafts OS1 and052 in the apparatus of FIG. 3.

For this purpose, the second input shaft IS2 is a hollow shaft, and thethird, fifth, and fourth input gears G3, G5, and G4 are disposed on thesecond input shaft IS2 in a named sequence from the front portion to therear portion in the apparatus of FIG. 3. At least a portion of the firstinput shaft IS1 is inserted in the second input shaft IS2, and thesixth, first and second input gears G6, G1, and G2 are disposed on aportion of the first input shaft IS1 penetrating the second input shaftIS2 in a named sequence from the front portion to the rear portion.

Therefore, the first synchronizer module SL1 is disposed on the frontportion of the first output shaft OS1, the third speed gear D3 isengaged with the third input gear G3, and the first speed gear D1 isengaged with the fifth input gear G5. The second synchronizer module SL2is disposed on the rear portion of the first output shaft OS1, thereverse speed gear RG is operably connected to the sixth input gear G6through the reverse speed device, and the second speed gear D2 isengaged with the second input gear G2.

In addition, the fourth synchronizer module SL4 is disposed at the frontportion of the second output shaft OS2, the seventh speed gear D7 isengaged with the third input gear G3, and the fifth speed gear D5 isengaged with the fourth input gear G4. The third synchronizer module SL3is disposed at the rear portion of the second output shaft OS2, thesixth speed gear D6 is engaged with the first input gear G1, and thefourth speed gear D4 is engaged with the second input gear G2.

Since constitution and operation of the apparatus of FIG. 3 are the sameas those of the apparatus of FIG. 1 except arrangement of thesynchronizer modules, detailed description thereof will be omitted.

According to various embodiments of the present invention, the secondspeed gear and the fourth speed gear are simultaneously engaged with thesecond input gear, and the third speed gear and the seventh speed gearare simultaneously engaged with the third input gear.

Since seven forward speeds can be achieved but the number of input gearsdisposed on the input shafts can be minimized, it is unnecessary toelongate a length of the input shafts. Therefore, layout change ofengine compartments and other design change due to increase of thelength of the transmission may be prevented.

In addition, the second speed gear and the fourth speed gear havingcomparatively large gear ratio difference therebetween aresimultaneously engaged to the second input gear, and the third speedgear and the seventh speed gear having comparatively large gear ratiodifference therebetween are simultaneously engaged to the third inputgear. Therefore, drivability and fuel economy may be improved bypreventing distortion of step ratios at the high-speed region.

For convenience in explanation and accurate definition in the appendedclaims, the terms front or rear, and etc. are used to describe featuresof the exemplary embodiments with reference to the positions of suchfeatures as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A power transmitting apparatus for a vehiclecomprising: a variable connecting device including a first clutch and asecond clutch and selectively outputting torque of a power sourcethrough the first clutch and the second clutch; an input deviceincluding a first input shaft selectively connected to the power sourcethrough the second clutch and provide with first, second, and sixthinput gears fixedly disposed on an exterior circumference thereof, and asecond input shaft selectively connected to the power source through thefirst clutch and provided with third, fourth, and fifth input gearsfixedly disposed on an exterior circumference thereof; a speed outputdevice including a first output shaft disposed in parallel with thefirst and second input shafts, a first speed output unit disposed on thefirst output shaft and provided with first and second synchronizermodules, a second output shaft disposed in parallel with the first andsecond input shafts, and a second speed output unit disposed on thesecond output shaft and provided with third and fourth synchronizermodules; a reverse speed device including a reverse speed shaft and anidle gear and a reverse input gear fixedly disposed on the reverse speedshaft, wherein the idle gear is engaged with any one input gear on thefirst and second input shafts and the reverse input gear is engaged withany one synchronizer module disposed on the first output shaft; andfirst, second, third, fourth, fifth, sixth, and seventh speed gears anda reverse speed gear included in the first, second, third, and fourthsynchronizer modules; wherein the second speed gear and the fourth speedgear are simultaneously engaged with the second input gear disposed onthe first input shaft, and the third speed gear and the seventh speedgear are simultaneously engaged with the third input gear disposed onthe second input shaft.
 2. The power transmitting apparatus of claim 1,wherein the first input shaft is a hollow shaft and the sixth, first andsecond input gears are disposed on the exterior circumference of thefirst input shaft in a named sequence from a front portion to a rearportion, and at least a portion of the second input shaft is inserted inthe first input shaft, and the third, fifth and fourth input gears aredisposed on a portion of the second input shaft penetrating the firstinput shaft in a named sequence from a front portion to a rear portion.3. The power transmitting apparatus of claim 2, wherein the firstsynchronizer module includes the third speed gear engaged with the thirdinput gear and the first speed gear engaged with the fifth input gear.4. The power transmitting apparatus of claim 2, wherein the secondsynchronizer module includes the reverse speed gear engaged with thereverse input gear connected to the idle gear engaged with the sixthinput gear through the reverse speed shaft, and the second speed gearengaged with the second input gear.
 5. The power transmitting apparatusof claim 2, wherein the third synchronizer module includes the sixthspeed gear engaged with the first input gear and the fourth speed gearengaged with the second input gear.
 6. The power transmitting apparatusof claim 2, wherein the fourth synchronizer module includes the seventhspeed gear engaged with the third input gear and the fifth speed gearengaged with the fourth input gear.
 7. The power transmitting apparatusof claim 1, wherein the sixth, first and second input gears are disposedon the exterior circumference of the first input shaft in a namedsequence from a front portion to a rear portion, the second input shaftis a hollow shaft and the third, fifth and fourth input gears aredisposed on the exterior circumference of the second input shaft in anamed sequence from a front portion to a rear portion, and at least aportion of the first input shaft is inserted in the second input shaft.8. The power transmitting apparatus of claim 7, wherein the firstsynchronizer module includes the third speed gear engaged with the thirdinput gear and the first speed gear engaged with the fifth input gear.9. The power transmitting apparatus of claim 7, wherein the secondsynchronizer module includes the reverse speed gear engaged with thereverse input gear connected to the idle gear engaged with the sixthinput gear through the reverse speed shaft, and the second speed gearengaged with the second input gear.
 10. The power transmitting apparatusof claim 7, wherein the third synchronizer module includes the sixthspeed gear engaged with the first input gear and the fourth speed gearengaged with the second input gear.
 11. The power transmitting apparatusof claim 7, wherein the fourth synchronizer module includes the seventhspeed gear engaged with the third input gear and the fifth speed gearengaged with the fourth input gear.
 12. A power transmitting apparatusfor a vehicle comprising: a first clutch connected to a power source andselectively outputting torque of the power source; a second clutchconnected to the power source and selectively outputting the torque ofthe power source; a first input shaft being a hollow shaft, selectivelyreceiving the torque of the power source through the second clutch, andprovided with sixth, first and second input gears disposed on anexterior circumference thereof in a named sequence; a second input shaftpenetrating the first input shaft without rotational interferencetherebetween, selectively receiving the torque of the power sourcethrough the first clutch, and provided with third, fifth and fourthinput gears disposed on an exterior circumference thereof in a namedsequence; first and second output shafts disposed in parallel with thefirst and second input shafts; a first synchronizer module disposed onthe first output shaft, and including a third speed gear engaged withthe third input gear and a first speed gear engaged with the fifth inputgear; a second synchronizer module disposed on the first output shaft,and including a reverse speed gear engaged with a reverse input gearconnected to an idle gear engaged with the sixth input gear through areverse speed shaft and a second speed gear engaged with the secondinput gear; a third synchronizer module disposed on the second outputshaft, and including a sixth speed gear engaged with the first inputgear and a fourth speed gear engaged with the second input gear; and afourth synchronizer module disposed on the second output shaft, andincluding a seventh speed gear engaged with the third input gear and afifth speed gear engaged with the fourth input gear.